The invention pertains to sensing devices and particularly to pressure sensing devices. More particularly, it pertains to diagnosis of pressure sensing devices.
In differential pressure sensors, one common field problem is the plugging of impulse lines. These lines are pipes or tubes that connect the sensor to the differential pressure producing element. In some cases, a blockage of the impulse line can create a pressure in the line that, when measured by the pressure differential reading of the sensor, will be on-scale thereby indicating normal operation while the process being monitored may have changed flow rates substantially. Despite the apparent normal operation, the sensor may actually be providing an erroneous output and reading. An illustrative example of such pressure sensor may be disclosed in U.S. Pat. No. 6,041,659, issued Mar. 28, 2000, to Douglas W. Wilda et al., entitled “Methods and Apparatus for Sensing Differential and Gauge Static Pressure in a Fluid Line”, which is hereby incorporated by reference in the present specification.